An image formation with a light-sensitive resin composition is used in a wide field such as a printing wiring plate, a printing plate, IC circuit, and a preparation of a color proof, and various processes are available according to the applications and forms thereof. In every case, it generally includes a process for providing a light-sensitive resin layer on a substrate, a process for imagewise irradiating a ray (hereinafter referred to as a pattern exposure), and a developing process. Of these processes, a representative one used as a developing solution in the developing process is roughly classified to an organic solvent series, an alkaline aqueous solution, and a water series. In recent years, it is going toward a light-sensitive resin composition capable of being developed in the alkaline aqueous solution or water from a viewpoint of a working environment, an air pollution and a water contamination.
UV radiation is most generally used for a pattern exposure of these light-sensitive resin compositions. That requires a sufficient image-forming performance with UV radiation to the light-sensitive resin composition, and various initiators which absorb the UV radiation to start a reaction are known. Too large UV absorbance of the light-sensitive resin composition prevents a sufficient amount of the UV radiation from reaching a bottom of the composition and accordingly generates a defect such as a reduction of a sensitivity and cutting off at a lower part (a portion close to a substrate) of a relief image. Accordingly, the UV absorbance of the light-sensitive resin composition can not simply be increased.
On the other hand, a sufficient UV absorbance is required to an image itself formed in some cases from a viewpoint of a light fastness and for a purpose of providing a back face exposure aptitude in which a formed image is used as a light-shielding pattern, a so-called self-alignment system. An addition of a so-called UV absorber is effective to meet the purpose of absorbing UV radiation. Such the example is described in, for example, JP-A-5-210009 (the term "JP-A" as used herein means an unexamined published Japanese patent application) and Japanese Patent Application No. 4-150691. However, an addition of the UV absorber in such an amount as capable of providing a light-sensitive resin composition with a sufficient UV absorbance causes UV radiation necessary for forming an image in a pattern exposure to be absorbed as well, and accordingly the problems such as a reduction of a sensitivity and cutting off at a lower part (a portion close to a substrate) of a relief image are generated.
For a purpose of solving these problems, there is described in, for example, JP-A-4-278901, a process in which for a purpose of providing UV radiation exposure aptitude passing through a formed image, an exposure is carried out via a specific filter which does not transmit a portion of an image already formed and allows only a light-sensitive wavelength for a light-sensitive layer which is to be newly exposed to transmit. However, there are involved in this system, the problems that the respective light-sensitive layers have to be set at the different light-sensitive wavelengths and that a specific filter has to be provided according to the compositions of the light-sensitive layers.
There is disclosed in, for example, JP-A-4-214530, an image forming process in which baking is carried out at 150.degree. to 300.degree. C. after forming an image with a photoresist to increase an absorbance of UV radiation and this is used as a light-shielding pattern.
Specifically, a positive working photoresist having an image formed therein is baked, a black resist is applied on the baked photoresist and dried, then the photoresist is exposed to light from the back side and developed, and then the positive working photoresist is puled off to provide a black image. The above process can certainly omit the use of a mask for exposure in the formation of a black image. However, when an RGB image with a black matrix such as a color filter for use, for example, in liquid crystal displays, it is difficult to form first an RGB image and then a black matrix. Further, in this composition, an increase in an absorbance after baking is extended to a long wavelength region (vicinity of 400 to 700 nm) and accordingly, a defect that an image completed has an inferior color tone is involved.
Thus, there is not known in an alkali developing type light-sensitive resin composition, a composition which has an excellent image forming performance in exposing and a sufficient UV absorbance after forming the image and which provides the image with a satisfactory color tone and enables to form the image without changing a usual process.
A number of compounds are known as UV absorbers. Typical such compounds are those having at least one hydroxyl group in the molecule. Typical examples of these compounds include 2-(2'-hydroxyphenyl)2H-benzotriazole derivatives and p-hydroxycyano-cinnamic acid derivatives. Other compounds such as 2-hydroxybenzophenone derivatives and salicylic acid aryl ester derivatives are also known as UV absorbers. Also, the compounds resulting from protecting at least one hydroxyl group (OH group) in these derivatives by a protective group or from converting it into a derived group (OR group) are known UV absorbers.
Examples of the compounds resulting from protecting at least one hydroxyl group (OH group) of 2-(2'-hydroxyphenyl)2H-benzotriazole derivatives by a protective group or from converting it into a derived group (OR group) are described in U.S. Pat. No. 3,936,418 containing as R an aryloxycarbonyl group; European Patent 180548 an acyl group, an alkyloxycarbonyl group or an acylcarbonyl group; U.S. Pat. No. 4,260,768 an acryloyl group; and JP-A-57-45169 an acetyl group; U.S. Pat. No. 4,041,011 disclosing a compound made in the bis form through a linking chain and an acyl group using a dicarboxylic acid; U.S. Pat. No. 3,936,418 disclosing a 2-(2'-hydroxyphenyl)2H-benzotriazole derivative with an acetyl group as R and also a formyl group.
Also, JP-A-58-38269 discloses compounds with an acyl group as R and containing a vinyl group; JP-A-57-45169 compounds with an acetyl group as R and a polymerizable group and polymeric compounds derived from these compounds.
Examples of compounds resulting from protecting a hydroxyl group (OH group) of p-hydroxycyanocinnamic acid by a protective group or from converting it into a derived group (OR group) are those described in JP-A-5-100417 including compounds having an alkoxycarbonylmethyl group as R and a polymerizable unsaturated double bond in a cinnamic ester moiety.
There are also many other known UV absorbing compounds such as 2-hydroxybenzophenone derivatives and salycilic acid aryl ester derivatives with at least one hydroxyl group (OH group) protected by a protective group or a derived group (OR group).
The compound itself obtained by protecting these hydroxy groups (OH groups) with any protective groups or converting them to derived groups (OR groups) also is a kind of a UV absorber. In fact, in the examples described above, these compounds are used as the UV absorber in many cases. However, the absorption wavelength region thereof is usually shifted to a short wavelength region as compared with the case of a hydroxy group, and a sufficient UV absorbance is not provided in an exposing wavelength (in and about 330 to 430 nm) usually used for forming an image with a photoresist. On the contrary, it is considered that if these compounds could be converted to a hydroxy product in any form, there could be provided a lower absorbance of UV radiation used for forming an image in exposing and a sufficient UV absorbance after forming the image.
There are described in, for example, U.S. Pat. No. 4,328,346, and JP-A-57-57772, 62-209087, 63-132978, and 1-258689 as an example in which such conversion is carried out, the examples of a photocurable coating composition in which a derivative of 2-(2'-hydroxy-phenyl)2H-benzotriazole in which at least one hydroxy group having a silane functional group is protected with a benzoyl group or a benzenrsulfonyl group is used as a precursor (it has a low UV absorbance in a light-sensitive wavelength region in itself but it is converted to a UV absorber in the light-sensitive wavelength region by a reaction and a processing thereafter) of a benzotriazole series UV absorber to convert it to a UV absorber utilizing a photo Fries rearrangement. However, the example of using them for forming an image in a process such as a development is not described in the publications described above. The similar reaction is described as well in Journal of Applied Polymer Science 28 1159 (1983) but an image formation by a process such as a development is not described as well.
The phenylbenzotriazole series compounds in which a hydroxy group is protected with a urethane bond are described in U.S. Pat. Nos. 4,061,652 and 4,179,548, and JP-A-52-68158, and it is described therein that it is used as a precursor of a UV absorber for a UV-curable resin. In these examples, splitting off is made by heating after curing with UV radiation. However, an example in which they are used for an image formation in a process such as a development is not described as well in this example.
Further, there is disclosed in U.S. Pat. No. 5,141,990, the example in which a compound obtained by protecting at least one hydroxy group of a derivative of a 2-(2'-hydroxyphenyl)2H-benzotriazole with a saturated acyl group or an acryloyl group is used as a precursor of a UV absorber to convert it to a UV absorber by a development. However, the development described herein corresponds to an after-exposure after curing with UV radiation and is an exposure further continued after wholly curing a UV-curing type coating material. Accordingly, it is not aimed at an image formation.
The examples of using these compounds, in which R is an acyl group, for an image-forming material are described in JP-A-64-23257, 64-19342, 64-9457, 64-7038, 64-7040, 64-9454, 64-13147, 2-77060, and 3-61946. However, all of them are used for a purpose of improving an image storing performance of a silver halide photographic light-sensitive material. Accordingly, an exposing wavelength resides in the visible region, and the form thereof is different from a purpose that light of an exposing wavelength (in the range of about 330 to about 430 nm) which is used for an image formation in a conventional photoresist is not absorbed in exposing.
Also, it is not described that the compounds resulting from protecting at least one hydroxyl group (OH group) of p-hydroxycyanocinnamic acid derivatives with a protective group or from converting it into a derived group (OR group) are used as precursors of UV absorbers and thereafter converted into p-hydroxycyanocinnamic acid derivatives. There is also no disclosure relating to alkali developing type photoresists such as those relating to the present invention.